DE102018202039A1 - Method for the projection lithographic transmission of an object structure arranged in an object field - Google Patents

Abstract

In the projection lithographic transmission of an object structure arranged in an object field to a substrate arranged in an image field (9), the image field (9) which can be illuminated with illumination light (2a) is first provided. In the image field (9), a portion of the substrate can be arranged. A target area (14a) is now exposed on the substrate (10) while the substrate (10) is displaced relative to the image field (9) along a scanning direction (13, y). Then, a gap (15) between the exposed target area (14a) and a further target area (14b) following in the scanning direction (y, 13) is shaded, as long as the gap (15) during the displacement of the substrate (10) relative to the image field (9 ) is displaced along the scanning direction (y, 13) through the image field (9). These exposing and shading steps are repeated until a predetermined number of target areas (14a, 14b, ...) are exposed. This results in an increased substrate or wafer throughput.

Description

The invention relates to a method for the projection lithographic transmission of an object structure arranged in an object field to a substrate arranged in an image field. Furthermore, the invention relates to an assembly for projection lithographic transmission of the object structure using the method, an optical system for projection lithographic transmission of an object structure with such an assembly, a projection exposure apparatus with such an optical system, a method for producing a micro- or nanostructured component using such a projection exposure apparatus and a microstructured or nanostructured component produced by means of such a production method using the transfer method.

A projection lithographic transmission method of the type mentioned is known for. B. from the DE 10 2005 034 991 A1 , from the US 2007/0236784 A1 , of the DE 10 2013 204 445 A1 and from the DE 10 2009 025 656 A1 ,

It is an object of the present invention to develop a transmission method of the aforementioned type such that its substrate or wafer throughput is increased.

This object is achieved by a transfer method with the features specified in claim 1.

According to the invention, it has been recognized that it is possible to perform an exposure of a plurality of successive target areas on the substrate, wherein the substrate is displaced along the scanning direction both when exposing the target areas and then relative to the image field, if a space between two target areas to be exposed by the Image field is shifted. The exposure of several target areas thus happens while the substrate is moved along one direction only, namely along the scanning direction. This leads to an increase in throughput in comparison with methods according to the prior art in which, after each target area exposure, the substrate is decelerated to a standstill or in which the substrate is displaced perpendicular to the scanning direction after exposure of a target area. A corresponding increase in throughput is the result in the transmission method compared to the prior art.

With the transfer method, a wafer throughput that is greater than 250 wafers per hour and, for example, greater than 300 wafers per hour, can be greater than 350 wafers per hour and even greater than 400 wafers per hour, can be achieved.

Displacement of the substrate during the same speed transfer process along the scan direction of claim 2 avoids unnecessary substrate acceleration.

If, according to claim 3, the object structure remains fixed in position relative to the object field during the transfer process, this leads to a simplification of the transfer process. Such a position fixation of the object structure during the target area exposure of the substrate is suitable for object structures which do not change along an otherwise used object scanning direction, ie in particular for object line structures. In particular, in the implementation of such a method object displacement can be omitted altogether, which not only simplifies the process, but also the required for performing the process projection exposure system.

The advantages of an assembly according to claim 4 correspond to those which have already been explained above with reference to the transmission method according to the invention. Due to the synchronized displacement on the one hand of the substrate with the substrate displacement drive and on the other hand the Abschottungsblende with the shutter displacement drive the targeted shading of the intermediate areas between the target areas to be exposed on the substrate is guaranteed.

A shading panel according to claim 5 is particularly well suited for carrying out the transfer method. The size of the aperture window ensures that the shading panel does not undesirably shade illuminating light when exposing the target areas.

A plurality of aperture portions according to claim 6 enables a shadowing of a corresponding plurality of spaces between each two successive target areas to be exposed on the substrate. The panel sections can be arranged like the rungs of a ladder. The panel sections can be held by lateral spars, which in turn can correspond to the spars of a ladder with regard to their arrangement. The number of aperture sections may be greater than 5 and may be for example 6, 7, 8, 9 or 10 and may be even greater.

If, according to claim 7, the diaphragm sections have a comparable or exactly the same extent in the scanning direction as the extension of the intermediate spaces in the scanning direction, a particularly effective shading of the intermediate spaces is achieved. During shading of the respective gap then the shading aperture with exactly the same scan speed moves as the substrate.

If, according to claim 8, an extension of the image field in the scanning direction is smaller than an extent of the respective intermediate spaces between the substrate target areas to be exposed, it is ensured in particular that no uncontrolled exposure of the adjacent target areas takes place during the shading of the respective gap.

The advantages of an optical system according to claim 9 including an imaging optics and an optical system according to claim 10 including an illumination optical system correspond to those which have already been explained above with reference to the assembly according to the invention.

The advantages of a projection exposure apparatus according to claim 11 correspond to those which have already been explained with reference to the assembly according to the invention.

An EUV light source according to claim 12 enables an extremely high structural resolution.

A DUV light source according to claim 13 enables a very large substrate or wafer throughput.

The advantages of a production method according to claim 14 and of a microstructured or nanostructured component according to claim 15 correspond to those which have already been explained above with reference to the projection exposure apparatus.

The component may be a semiconductor chip with an extremely high integration density or storage density.

• 1 schematisch und perspektivisch Hauptkomponenten einer Projektionsbelichtungsanlage für die Projektionslithografie;
• 2 eine Momentaufnahme von Relativpositionen zweier zu belichtender Substrat-Zielbereiche, eines mit Beleuchtungslicht der Projektionsbelichtungsanlage ausgeleuchteten Beleuchtungsfeldes sowie einer in der dargestellten Ausführung zwei Blendenabschnitte aufweisenden Abschattungsblende zum Abschatten von Zwischenräumen zwischen den zu belichtenden Substrat-Zielbereichen, während ein in der 2 rechts dargestellter, führender Zielbereich belichtet wird;
• 3 die Komponenten nach 2 in einer weiteren, nachfolgenden Momentaufnahme in dem Zeitpunkt, in dem eine Belichtung des führenden Substrat-Zielbereichs gerade vollendet wird;
• 4 die Komponenten nach 3 in dem nachfolgenden Moment, in dem mit einer Belichtung des folgenden Substrat-Zielbereichs nach Abschattung des Zwischenraums durch einen Blendenabschnitt der Abschattungsblende begonnen wird; und
• 5 die Komponenten nach 4 in einem nachfolgenden Moment, in dem der folgende Substrat-Zielbereich belichtet wird.

An embodiment of the invention will be explained in more detail with reference to the drawing. In this show:

• 1 schematic and perspective main components of a projection exposure apparatus for projection lithography;
• 2 a snapshot of relative positions of two substrate target areas to be exposed, an illumination field illuminated by illumination light of the projection exposure apparatus and a shading diaphragm having two diaphragm sections in the illustrated embodiment for shading gaps between the substrate target areas to be exposed, while one in the 2 illuminated on the right-hand side;
• 3 the components after 2 in another subsequent snapshot at the time an exposure of the leading substrate target area is just completed;
• 4 the components after 3 in the subsequent moment in which an exposure of the following substrate target area after shading of the gap by a diaphragm portion of the shading diaphragm is started; and
• 5 the components after 4 in a subsequent moment in which the following substrate target area is exposed.

1 shows schematically and in perspective a projection exposure system 1 for projection lithography or microlithography. To the projection exposure system 1 belongs to a light or radiation source 2 , At the light source 2 it can be an EUV light source with an emitted useful radiation in the range between 5 nm and 30 nm. It may be a plasma source or a source based on a synchrotron or on a free electron laser. Alternatively, it may be at the light source 2 also be one that emits DUV light, for example light with a wavelength of 193 nm. At the light source 2 So it can be an excimer laser.

Information on the radiation source is the expert z. B. in the US 6,859,515 B2 , of the DE 10 2005 034 991 A1 and the references given there.

An illumination system of the projection exposure apparatus 1 has an illumination optics 3 for exposing one with an object field 4 coincident illumination field in an object plane. The illumination field can also be larger than the object field 4 , An object line structure is exposed 5 in the object field 4 lies and the part of an object in the form of a reticle 6 is which of an object holder 7 is held. The reticle 6 is also called lithography mask. The object line structure 5 has on the reticle 6 an extent that is at least as large as the object field 4 and which may be slightly larger than the object field 4 ,

The object holder 7 may be displaceable over an object displacement drive along an object displacement direction. As far as the object line structure 5 is projected as part of the projection exposure, there is no drive of the reticle 6 over the object holder 7 so that the reticle 6 relative to the optical components of the projection exposure apparatus 1 firmly fixed in position.

A projection optics 8th serves to represent the object field 4 in a picture field 9 in an image plane. Components of the projection optics 8th are in the 1 shown schematically as lenses. It may vary depending on the wavelengths of illumination light used by the light source 2 also act around mirrors. The object line structure is shown 5 on a photosensitive layer in the area of the image field 9 arranged wafers 10 , In the picture box 9 is thus a section of the wafer or substrate 10 arranged. The wafer 10 is from a wafer holder 11 held. The wafer holder 11 is via a wafer displacement drive 12 along a scanning direction 13 displaced.

To facilitate the description of positional relationships is in the 1 a Cartesian xyz coordinate system as a global coordinate system for the description of the positional relationships of components of the projection exposure apparatus 1 located. The x-axis is parallel to the image plane and perpendicular to the scan direction 13 , The y-axis is parallel to the scan direction 13 , The z-axis is perpendicular to the image plane.

Shown in the 1 schematically the course of three emanating from different object field points principal rays CR on the one hand between the reticle 7 and the projection optics 8th and on the other hand, between the projection optics 8th and the wafer 10 ,

One each in total on the wafer 10 contiguous target area is in the 1 dash-dotted lines shown at 14a / b. The currently exposed target area 14b, in which the image field 9 is arranged in the x-direction has the same extent as the image field 9 and is several times longer in the y-direction than the image field 9 , The entire target area 14b is due to the relative displacement of the wafer 10 to the picture field 9 exposed. Shown in the 1 schematically also another, in the scanning direction 13 leading target area 14a which leads the currently exposed target area.

Between the two target areas 14a . 14b is a not to be exposed space 15 ,

The target areas 14a . 14b on the wafer 10 are in the 1 shown greatly exaggerated. Actually lie on the wafer 10 in a series to be scanned, for example, ten consecutive target areas 14a . 14b . 14c , ... in front.

To the projection exposure system 1 still belongs to a shading panel 16 that in the 2 ff. is shown. The shading panel 16 can be near the object field 4 or near the image field 9 be arranged. The following description assumes that the shading aperture is near the image field 9 is arranged. In an arrangement near the object field 4 If necessary, the geometrical information given below and the dimensional data, insofar as they relate to the field, must comply with the (inverse) magnification of the projection optics 8th be scaled. As far as the projection optics 8th exemplarily the object field 4 by a factor 4 reduced to the image field 9 images (magnification 1 : 4), the dimensions given below, insofar as they relate to the image field, are for transmission to an arrangement of the shading stop 16 in the area of the object field 4 with the factor 4 to scale. In the case of the arrangement of the shade 16 in the area of the object field 4 otherwise, all subsequent explanations apply analogously.

The shading panel 16 stands with a diaphragm displacement drive 16a , the Indian 2 is shown schematically, in operative connection.

A central control device 16b (see. 1 ) stands with the wafer displacement drive 12 and the diaphragm displacement drive 16a in signal connection.

The shading panel 16 has a plurality of along the scanning direction 13 successive aperture sections 17 . 18 , of which in the embodiment according to the 2 ff. exactly two aperture sections 17 . 18 are shown. In fact, the shade can 16 more than two such successive diaphragm sections in the manner of the diaphragm sections 17 . 18 and may, for example, have three, four, five or even more such diaphragm sections, for example ten, along the scanning direction y successive diaphragm sections. Between two adjacent of these diaphragm sections, so for example between the in the 2 ff illustrated aperture sections 17 and 18 , is an aperture window 19 in front. The aperture sections 17 . 18 become by lateral spars 20 the shading panel 16 held. This arrangement of the aperture sections 17 . 18 reminiscent of the arrangement of rungs of a ladder.

Shown in the 2 ff. also a lighting field 21 in which the illumination light 2a on the wafer 10 falls. The image field 9 is in the 2 ff. dash-dotted lines and lies within the illumination field 21 ,

An extension F of the aperture window 19 along the scanning direction 13 is greater than an extension D _{I of} the image field 9 along the scanning direction 13 , This y-extension F of the aperture window 19 Depending on the design of the shading aperture, it is at least as large as the y-extent D _{I of} the image field 9 , It is therefore F ≥ D _I.

The extension D _{S of} the diaphragm sections 17 . 18 along the scanning direction 13 corresponds to an extension A _{D of} the respective spaces 15 between the adjacent target areas 14a . 14b along the scanning direction 13 , It therefore applies Ds = A _D.

In the illustrated embodiment, the extension D _{I of} the image field 9 along the scan direction smaller than the extension A _{D of} the spaces 15 between the target areas 14a . 14b , ... along the scanning direction 13 , So D _I <A _D. In principle, a design with D _I ≥ A _{D is} possible.

2 shows the situation in which the scan direction 13 leading wafer target area 14a with the illumination light 2a is exposed. The wafer 10 comes with the wafer displacement drive 12 in the scanning direction 13 with a constant during the entire subsequent process wafer displacement speed v _s in the positive y-direction shifted. In the current position after 2 is the shading screen 16 still, so becomes relative to the lighting field 21 not relocated.

3 shows the current situation where the leading target area 14a As far as in positive y-direction is scanned, that one is the leading target area 14a in the scanning direction 13 final edge 22 with the lighting field 21 exactly completes. At the same time 3 is the shading stop 16 relative to the illumination field 21 so shifts in positive y-direction that a leading aperture 23 of the aperture section 17 with the final target area edge 22 of the leading target area 14a exactly along the scanning direction 13 is at the same height. From this moment on 3 becomes the shading stop 16 in sync with the wafer 10 in the scanning direction 13 displaced at the same speed v _b = v _s .

A speed of the shading shutter v _b is between the momentary shots after the 2 and 3 from an aperture speed v _b = 0 to an aperture speed v _b = v _s accelerated.

4 shows one compared to 3 following moment in which the lighting field 21 completely out of the shadow of the panel section 17 has stepped out. Because the y-extension of the aperture section 17 equal to that of the gap 15 between the target areas 14a . 14b is the aperture section 17 the gap 15 in the period between the moments after the 3 and 4 completely shaded, so no illumination light 2a on the gap 15 could fall.

At the moment, after 4 fall a final aperture edge 24 of the aperture section 17 and a leading target area edge 25 of the target area 14b together.

5 now shows the further exposure of the following target area 14b and roughly indicates the analogous situation 1 ,

The lighting field 21 and accordingly the image field 9 are now in the aperture window 19 between the aperture sections 17 and 18 , The shading panel 16 shadows the illumination light 2a So in the picture field 9 not off. The exposure process of the following target area 14b again takes place until a final target area edge 22 of the target area 14b is reached. At this moment, the following diaphragm section 18, which was previously accelerated accordingly, again exactly at the level of the edge of the illumination field facing it 21 , so now the aperture section 18 the gap 15 between the target areas 14b and 14c can shadow.

The actual extensions of the panel sections 17 . 18 the shading aperture in the scanning direction 13 can deviate to scale from those in the 2 ff. are shown. The diaphragm sections may have y-extensions D _S in the range, for example, from 0.1 mm to 1.0 mm. Also the y-extension of the illumination field 21 may range between 0.1 mm and 2.0 mm, especially in the range between 0.1 mm and 1.0 mm.

Overall, the following procedure is therefore carried out:

First, this is done with the illumination light 2a illuminable field of view 9 provided in which a portion of the wafer 10 can be arranged. It will now be the target area 14a on the wafer 10 exposed while the wafer 10 relative to the image field 9 along the scanning direction y and 13 is displaced. Subsequently, the gap 15 between the exposed target area 14a and in the scanning direction 13 ff. further target area 14b shaded as long as the gap 15 during the displacement of the substrate 10 relative to the image field 9 along the scanning direction 13 through the picture field 9 is relocated. These steps "exposure of the target area" and "shadowing of the gap" are then repeated until a predetermined number of target areas 14a . 14b . 14c ... is exposed.

During the repetitive execution of these steps, the wafer becomes 10 at the same speed v _s along the scanning direction 13 or y relocated. The object line structure 5 remains relative to the object field during repeated execution 4 fix in position.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005034991 A1 [0002, 0022]
• US 2007/0236784 A1 [0002]
• DE 102013204445 A1 [0002]
• DE 102009025656 A1 [0002]
• US Pat. No. 685,951 B2 [0022]

Claims (15)

Process for the projection lithographic transmission of an object structure (5) arranged in an object field (4) onto a substrate (10) arranged in an image field (9), comprising the following steps: Providing the illumination field (2 a) illuminatable image field (9), in which a portion of the substrate (10) can be arranged, Exposing a target area (14a) on the substrate (10) while the substrate (10) is displaced relative to the field of view (9) along a scanning direction (y, 13), Shadowing of a gap (15) between the exposed target area (14a) and a further target area (14b) following in the scan direction (y, 13), as long as the gap (15) during the displacement of the substrate (10) relative to the image field (9) along the scanning direction (y, 13) is displaced by the image field (9), - repeating the steps of exposure and shadowing until a predetermined number of target areas (14a, 14b, 14c, ...) is exposed. Method according to Claim 1 , characterized in that the substrate (10) is displaced along the scanning direction (y, 13) at the same speed (vs) during the repeated execution of the steps of exposure and shading. Method according to Claim 1 or 2 , characterized in that the object structure (5) remains fixed in position during the repeated execution of the steps of exposure and shading relative to the object field (4). An assembly for the projection lithographic transfer of an object structure (5) to a substrate (10) arranged in an image field (9) using a method according to one of the Claims 1 to 3 with a substrate holder (11) for holding the substrate (10) during the exposure of an image field (9) which can be illuminated with illumination light (2a) with the illumination light (2a), with a substrate displacement drive (12) for displacing the substrate holder (11) relative to the image field (9) along the scan direction (y, 13) during the exposure of the target areas (14a, 14b, 14c, ...), - with a longitudinal direction of the scan direction (y, 13) synchronized with the substrate holder (11) displaceable Shading diaphragm (16) for shading the gap (15) between the exposed target area (14a; 14b; 14c; ...) and the further target area (14b; 14c; ...) following in the scanning direction (y, 13), as long as the Interspace (15) during the displacement of the substrate (10) relative to the image field (9) along the scanning direction (y, 13) is displaced by the image field (9), - relative to a diaphragm displacement drive (16a) for displacing the Abschattungsblende (16) to the image field (9) along the scan direction (y, 13 ), - with a control device (16b) which is in signal communication with the substrate displacement drive (12) and the diaphragm displacement drive (16a). Assembly after Claim 4 , characterized in that the shading diaphragm (16) has a plurality of diaphragm sections (17, 18) which follow one another along the scanning direction (y, 13), an aperture window (19) being present between two adjacent diaphragm sections (17, 18) whose extension (FIG. F) along the scanning direction (y, 13) is at least as large as an extension (D _I ) of the image field (9) in the scanning direction (y, 13). Assembly after Claim 4 , characterized in that the Abschattungsblende (16) has at least five such diaphragm sections (17, 18, ...). Assembly according to one of Claims 4 to 6 , characterized in that an extension (D _s ) of the diaphragm sections (17, 18) along the scanning direction (y, 13) of an extension (A _D ) of the intermediate spaces (15) between the target areas (14a, 14b, 14c, ... ) along the scanning direction (y, 13). Assembly according to one of Claims 4 to 7 , characterized in that an extension (D _I ) of the image field (9) in the scanning direction (y, 13) is smaller than an extension (A _D ) of the intermediate spaces (15) between the target regions (14a, 14b, 14c, .. .) along the scanning direction (y, 13) corresponds. Optical system for the projection lithographic transmission of an object structure (5) arranged in an object field (4) on a substrate (10) arranged on the image field (9), with an assembly according to one of Claims 4 to 8th , - with an imaging optical system (8) for imaging the object field (4) into the image field (9). Optical system after Claim 9 , characterized by illumination optics (3) for providing the object field (4) illuminated by the illumination light (2a). Projection exposure system (1) with an optical system according to Claim 10 and a light source (2) for generating the illumination light (2a). Projection exposure system (1) according to Claim 11 , characterized by an EUV light source. Projection exposure system (1) according to Claim 11 , characterized by a DUV light source. Method for producing a microstructured or nanostructured component with the following steps: Providing a projection exposure apparatus (1) according to one of the Claims 11 to 13 Providing a wafer, providing a lithography mask, projecting at least a portion of the lithography mask onto a target area of a photosensitive layer of the wafer Assistance of the projection optics (8) of the projection exposure apparatus (1) using the transmission method according to one of Claims 1 to 3 , Component produced by a method according to Claim 14 ,

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